Master Thesis

Current research (PhD-Thesis): Regulation of plant anti-herbivore defenses in time and spaceUsing cytokinins to manipulate developmentally regulated defense mechanisms in Nicotiana attenuata
I am investigating the role of cytokinins in the developmental regulation of anti-herbivore defenses and defense-strategies on the model plant Nicotiana attenuata and two native herbivorous insect species: The chewing larvae of Manduca sexta (Lepidoptera, Sphingidae) and the sap-sucking bug Tupiocoris notatus (Heteoptera, Miridae).
Herbivore induced defenses are costly for a plant to produce and its regulation will affect plant growth and fitness. Its induction upon herbivore attack is known to be tightly regulated. The optimal defense theory (ODT) predicts that the concentrations of defense metabolites in plant tissues are positively correlated with their fitness values and their probability of perceiving herbivore attack. Although it is well-known for many plant species that defenses are developmentally regulated, the underlying mechanisms remained unknown.
I am anlyzing the role of cytokinins in the regulation of distribution patterns of herbivory inducible defenses predicted by the ODT. Our results provide evidence that the developmental regulation of growth hormones, such as cytokinins, plays a key role in establishing optimal defense patterns in plants.
Deregulation of developmental processes by manipulating cytokinin levels with transgenic plants decreases resistance against two major herbivores M. sextaand T. notatus. I am working on the role of cytokinins in herbivory-induced senescence. We hypothesize that senescence-related processes and their regulation by cytokinins are integral components of plant responses to herbivore attack. Inhibiting senescence might influence a plants fitness differentially when herbivores are present than without herbivore pressure.T. notatus, a cell content feeder seems to influence cytokinin levels actively when feeding on N. attenuata. There is evidence that upregulation of cytokinin levels is positively influencing T. notatus performance on N. attenuata. By using transgenic plants impaired in cytokinin biosynthesis or perception, I am trying to find out how T. notatus is influencing a plants cytokinin-metabolism and what consequences this has for the resistance against T. notatus.
Those aspects seem to play a role in the circadian regulation of plant metabolisms as well, which I am trying to unravel by using transgenic plants that are impaired in parts of their internal circadian clock to explore their influence on N. attenuatas interaction with T. notatus under greenhouse- and field-conditions.